1. Field of the Invention
The present invention relates to a transmission type or transmission-reflection double type liquid-crystal display device which can be easily reduced both in thickness and in weight and which is excellent in display quality.
The present application is based on Japanese Patent Application No. 2000-178033, which is incorporated herein by reference.
2. Description of the Related Art
Greater reduction in thickness, size and weight of transmission type liquid-crystal display devices has been demanded for the purposes of suppressing increase in weight which is accompanied by increase in size of television and personal computer display screens, reducing in size and weight of portable personal computers and portable telephone sets, etc. In the meanwhile, it is however difficult to reduce thickness, size and weight of a transmission type liquid-crystal display device if the display device is provided with a back-lighting system using a background-art bottom type or side-lighting type light pipe. Incidentally, the bottom type back-lighting system generally has a thickness of not smaller than 4 mm because a light source, a light diffusing plate and a reflection plate are disposed just under a liquid-crystal display panel. Even the side-lighting type light pipe has a thickness of not smaller than 1 mm under the necessity of light transmission. When a light diffusing plate, a reflection plate, a prism sheet, etc. are disposed on the side-lighting type light pipe, the total thickness generally reaches a value of not smaller than 3 mm.